The present invention relates to a hydraulically-actuated starting clutch for a continuously variable transmission in an automotive vehicle. Continuously variable transmissions have been known for a number of years as a driving means located between a vehicle engine and the road engaging wheels to provide a smooth acceleration without the usual shifting of gears by clutches and brake bands in an automatic transmission. A continuously variable transmission conventionally includes a pair of variable sheave pulleys, an endless belt extending between and in driving engagement with the pulleys and control means to alter the effective pulley diameters and thus change the belt ratio during operation of the vehicle.
In automotive applications, a hydraulically-actuated clutch is required on the driven pulley shaft as a starting device and to drive a shaft leading to forward/reverse gearing to drive the final differential for the road-engaging wheels. The starting clutch is positioned on the driven pulley shaft so that the pulleys can be constantly rotating in one direction and rotation is not interrupted when shifting from forward to reverse for vehicle operation. Thus, initiating movement of the vehicle is accomplished by a speed responsive friction starting device wherein the clutch is controlled by the control means for the pulleys.
In some transmission applications, it is desirable to use a two-friction plate clutch having an intermediate separator plate between the friction clutch plates and cooperating with the end plate and the movable pressure plate in the clutch housing. However, in clutch operation, the transmitted load tends to be concentrated toward the outer diameter of the friction plates which results in heavy load concentration at localized areas on the linings resulting in glazing and overheating thereof. The present invention overcomes the above-noted problem.